In recent years, infrared thermometers have come into wide use for detection of temperature of adults. For core temperature readings, infrared thermometers which are adapted to be inserted into the patient's ear have been very successful. Early infrared thermometers were adapted to extend into the ear canal in order to view the tympanic membrane and provide an uncorrected, direct reading of tympanic temperature which correlates with pulmonary artery temperature. More recently, however, to provide for greater comfort and ease of use, ear thermometers have been designed to provide corrected readings of the generally cooler distal ear canal. Such thermometers measure temperature of distal ear canal tissue and calculate arterial core temperature via heat balance.
It has been previously proposed to provide a sanitary cover or sheath for the probe which is inserted into the ear canal to minimize contamination and spreading of bacteria and viruses between patients. One such disposable speculum is disclosed in U.S. Pat. No. 4,662,360 to O'Hara et al., the contents of which are incorporated herein by reference.
U.S. Pat. No. 4,993,419 to Pompei et al., the contents of which are also incorporated herein by reference, provides an improved sanitary cover in the form of a removable plastic sheet which is stretched over the end of the probe. The sheet is retained on the probe by posts on the sides of the probe over which holes in the sheet are positioned.
To avoid clinical difficulties in using ear thermometers, particularly with neonates, axillary (underarm) infrared thermometers have been introduced. Infrared thermometers designed for axillary temperature measurements are presented in U.S. patent application Ser. Nos. 08/469,484, 08/881,891, and U.S. Pat. No. 5,874,736 to Pompei, the entire teachings of which are incorporated herein by reference. In each of those devices, an infrared detector probe extends from a temperature display housing and may easily slide into the axilla to lightly touch the apex of the axilla and provide an accurate infrared temperature reading in as little as one-half second. The axillary thermometer also relies on the arterial heat balance approach to provide arterial, oral or rectal temperature.
The axillary infrared thermometer has found great utility not only with neonates but as a screening tool in general, and especially for small children where conventional temperature measurements such as a thermometer under the tongue or a rectal thermometer are difficult. These systems also provide disposable sanitary covers for the clinical market which include plastic sheets similar to those disclosed in the '419 Pompei patent. When these thermometers are adapted for household use, concerns for patient cross-contamination associated with clinical temperature detectors are not so significant and therefore disposable covers have not always been employed.
However, for purposes of accuracy of measurement, a thin transparent film is provided over the viewing area of the infrared sensor. Without the film, any evaporation from the moist axillary region results in a temperature reduction at the target surface thereby reducing accuracy in the temperature reading. The film is pressed against the target surface, thus trapping the moisture and preventing evaporation. The thin film quickly equilibrates to the temperature of the target surface for an accurate reading.